"Negative emissions" included in emissions scenarios, massive CDR needed to reach climate goals

本站收录: 2026-05-21

[00:00:00]One of the criticisms of CDR is that it's a moral hazard, that it will prevent us from reducing our emissions.

[00:00:06]And I always tell people, "No, no, no.

[00:00:08]We have to do it in addition to getting our emissions down to zero as rapidly as possible."

[00:00:14]But when you embed CDR into the model, and people don't know this, and then you tell them there is a carbon budget left, but that Let me ask my first question.

[00:00:25]If you remove CDR from the models, is there any carbon budget left?

[00:00:30]Yes, it depends purely on the goal. And but and I 100% agree with how you formulated the position with respect to CDR. But let's say 1.5°.

[00:00:43]1.5° the carbon budget at the moment is a is a best 100 gigatons of CO2. And that is left starting from the 130 gigatons. I mean it's something maybe in reality, but okay. Yeah.

[00:00:55]>> [laughter] >> Let's Let's assume an extremely ridiculous optimistic scenario via mitigation.

[00:01:04]And let's assume that exactly the same the EU now has promised itself. Also, let's see where and that is going to zero in 2050.

[00:01:16]So, if we do that via first stabilizing emissions in and then go down, we emit 600 gigatons of CO2. It's easily calculated 5 * 2 the 40 gigatons plus the 20 gigatons on average in the next 20 years. So, you have 600 gigatons. So, your overshoot is already 500 gigatons of CO2.

[00:01:43]So, the only way to come back to 1.5, and I'm assuming that things work nicely in the carbon cycle, uh would be to at least remove another 500 gigatons CO2 from the atmosphere.

[00:01:57]If you want to do that in this century, you're already looking at minus 10 gigatons on average in the second half of the century. And so for 1.5 we have put ourselves in a situation that the only way to reach it is not with some CDR, it's actually already with quite massive CDR.

[00:02:19]Right. Um which is very unfortunate because CDR goes with land use if it's bioenergy CCS or afforestation it goes with depleting fossil fuel reservoirs where we put if we use it in that way it goes with energy use for enhanced weathering and all these all these technologies have downsides. Correct.

[00:02:44]And so in reality, I 100% agree with you and the we have we have a situation where we should first of all close the tap and then can also start mopping. Um and we have to do both and it is not useful to do only CDR and not mitigate. The formulation is slightly different you say with with with with still the same dangerous consequences.

[00:03:10]So in the carbon budget estimates that are published by working group one and they have and that's for instance Forster et al last year in those estimates there is no CDR.

[00:03:22]Those are simply climate science based.

[00:03:25]They use these small climate models to explore what is the cumulative CO2 that we can admit to stay with a certain probability below a certain temperature outcome.

[00:03:36]Then we come in. And we use these small climate models as well to define a trajectory that is consistent still with this climate goal. And for 1.5 as I just I give this example it is not possible to get an outcome without for for two degrees in practical terms at some point is it's not possible anymore but by building it in indeed we can give this false perception okay 1.5 was almost impossible 10 years ago and now it's let's say 1.7 was almost impossible 10 years ago and it's now still almost impossible but a bit more negative emissions and and it could lead to a lullaby indeed and that is that is really important for my community to communicate we are actually in a in extreme extremely dangerous situation you can only reach this Paris goal targets by doing maximum emission reduction plus additionally so much CDR I think it is There is no graph at least in your paper showing how much of the CO greenhouse gas or CO2 equivalent emissions is negative emissions right You can I think it for the net negative you can see it of course because then it go the whole graph goes net No I I don't think we have included it it will be part of the so what we are also going to do is to publish a few papers after this where the integrated assessment modeling teams will explain how the pathways look like in detail and and there there is one paper specifically discussing the CDR component of these scenarios Good thanks